# -*- coding: utf-8 -*-
#
# This file is part of moses.  Its use is licensed under the GNU Lesser General
# Public License version 2.1 or, at your option, any later version.

#

"""
Note: This Python (de-)tokenizer requires the following dependencies:
To Install
====
$ pip install -U six nltk
$ python -m nltk.downloader perluniprops
$ python -m nltk.downloader nonbreaking_prefixes
"""
from __future__ import print_function
import re

from six import text_type

from nltk.tokenize.api import TokenizerI
from nltk.tokenize.util import is_cjk
from nltk.corpus import perluniprops, nonbreaking_prefixes


class MosesTokenizer(TokenizerI):
    """
    This is a Pythonim port of the Moses Tokenizer from
    https://github.com/moses-smt/mosesdecoder/blob/master/scripts/tokenizer/tokenizer.perl
    >>> tokenizer = MosesTokenizer()
    >>> text = u'This, is a sentence with weird\xbb symbols\u2026 appearing everywhere\xbf'
    >>> expected_tokenized = u'This , is a sentence with weird \xbb symbols \u2026 appearing everywhere \xbf'
    >>> tokenized_text = tokenizer.tokenize(text, return_str=True)
    >>> tokenized_text == expected_tokenized
    True
    >>> tokenizer.tokenize(text) == [u'This', u',', u'is', u'a', u'sentence', u'with', u'weird', u'\xbb', u'symbols', u'\u2026', u'appearing', u'everywhere', u'\xbf']
    True
    The nonbreaking prefixes should tokenize the final fullstop.
    >>> m = MosesTokenizer()
    >>> m.tokenize('abc def.')
    [u'abc', u'def', u'.']
    The nonbreaking prefixes should deal the situation when numeric only prefix is the last token.
    In below example, "pp" is the last element, and there is no digit after it.
    >>> m = MosesTokenizer()
    >>> m.tokenize('2016, pp.')
    [u'2016', u',', u'pp', u'.']
    >>> sent = "This ain't funny. It's actually hillarious, yet double Ls. | [] < > [ ] & You're gonna shake it off? Don't?"
    >>> m.tokenize(sent, escape=True)
    ['This', 'ain', '&apos;t', 'funny', '.', 'It', '&apos;s', 'actually', 'hillarious', ',', 'yet', 'double', 'Ls', '.', '&#124;', '&#91;', '&#93;', '&lt;', '&gt;', '&#91;', '&#93;', '&amp;', 'You', '&apos;re', 'gonna', 'shake', 'it', 'off', '?', 'Don', '&apos;t', '?']
    >>> m.tokenize(sent, escape=False)
    ['This', 'ain', "'t", 'funny', '.', 'It', "'s", 'actually', 'hillarious', ',', 'yet', 'double', 'Ls', '.', '|', '[', ']', '<', '>', '[', ']', '&', 'You', "'re", 'gonna', 'shake', 'it', 'off', '?', 'Don', "'t", '?']
    """

    # Perl Unicode Properties character sets.
    IsN = text_type("".join(perluniprops.chars("IsN")))
    IsAlnum = text_type("".join(perluniprops.chars("IsAlnum")))
    IsSc = text_type("".join(perluniprops.chars("IsSc")))
    IsSo = text_type("".join(perluniprops.chars("IsSo")))
    IsAlpha = text_type("".join(perluniprops.chars("IsAlpha")))
    IsLower = text_type("".join(perluniprops.chars("IsLower")))

    # Remove ASCII junk.
    DEDUPLICATE_SPACE = r"\s+", r" "
    ASCII_JUNK = r"[\000-\037]", r""

    # Neurotic Perl heading space, multi-space and trailing space chomp.
    # These regexes are kept for reference purposes and shouldn't be used!!
    MID_STRIP = r" +", r" "  # Use DEDUPLICATE_SPACE instead.
    LEFT_STRIP = r"^ ", r""  # Uses text.lstrip() instead.
    RIGHT_STRIP = r" $", r""  # Uses text.rstrip() instead.

    # Pad all "other" special characters not in IsAlnum.
    PAD_NOT_ISALNUM = "([^{}\s\.'\`\,\-])".format(IsAlnum), r" \1 "

    # Splits all hypens (regardless of circumstances), e.g.
    # 'foo -- bar' -> 'foo @-@ @-@ bar' , 'foo-bar' -> 'foo @-@ bar'
    AGGRESSIVE_HYPHEN_SPLIT = (
        "([{alphanum}])\-(?=[{alphanum}])".format(alphanum=IsAlnum),
        r"\1 \@-\@ ",
    )

    # Make multi-dots stay together.
    REPLACE_DOT_WITH_LITERALSTRING_1 = r"\.([\.]+)", " DOTMULTI\1"
    REPLACE_DOT_WITH_LITERALSTRING_2 = r"DOTMULTI\.([^\.])", "DOTDOTMULTI \1"
    REPLACE_DOT_WITH_LITERALSTRING_3 = r"DOTMULTI\.", "DOTDOTMULTI"

    # Separate out "," except if within numbers (5,300)
    # e.g.  A,B,C,D,E > A , B,C , D,E
    # First application uses up B so rule can't see B,C
    # two-step version here may create extra spaces but these are removed later
    # will also space digit,letter or letter,digit forms (redundant with next section)
    COMMA_SEPARATE_1 = "([^{}])[,]".format(IsN), r"\1 , "
    COMMA_SEPARATE_2 = "[,]([^{}])".format(IsN), r" , \1"

    # Attempt to get correct directional quotes.
    DIRECTIONAL_QUOTE_1 = r"^``", r"`` "
    DIRECTIONAL_QUOTE_2 = r'^"', r"`` "
    DIRECTIONAL_QUOTE_3 = r"^`([^`])", r"` \1"
    DIRECTIONAL_QUOTE_4 = r"^'", r"`  "
    DIRECTIONAL_QUOTE_5 = r'([ ([{<])"', r"\1 `` "
    DIRECTIONAL_QUOTE_6 = r"([ ([{<])``", r"\1 `` "
    DIRECTIONAL_QUOTE_7 = r"([ ([{<])`([^`])", r"\1 ` \2"
    DIRECTIONAL_QUOTE_8 = r"([ ([{<])'", r"\1 ` "

    # Replace ... with _ELLIPSIS_
    REPLACE_ELLIPSIS = r"\.\.\.", r" _ELLIPSIS_ "
    # Restore _ELLIPSIS_ with ...
    RESTORE_ELLIPSIS = r"_ELLIPSIS_", r"\.\.\."

    # Pad , with tailing space except if within numbers, e.g. 5,300
    # These are used in nltk.tokenize.moses.penn_tokenize()
    COMMA_1 = "([^{numbers}])[,]([^{numbers}])".format(numbers=IsN), r"\1 , \2"
    COMMA_2 = "([{numbers}])[,]([^{numbers}])".format(numbers=IsN), r"\1 , \2"
    COMMA_3 = "([^{numbers}])[,]([{numbers}])".format(numbers=IsN), r"\1 , \2"

    # Pad unicode symbols with spaces.
    SYMBOLS = "([;:@#\$%&{}{}])".format(IsSc, IsSo), r" \1 "

    # Separate out intra-token slashes.  PTB tokenization doesn't do this, so
    # the tokens should be merged prior to parsing with a PTB-trained parser.
    # e.g. "and/or" -> "and @/@ or"
    INTRATOKEN_SLASHES = (
        "([{alphanum}])\/([{alphanum}])".format(alphanum=IsAlnum),
        r"$1 \@\/\@ $2",
    )

    # Splits final period at end of string.
    FINAL_PERIOD = r"""([^.])([.])([\]\)}>"']*) ?$""", r"\1 \2\3"
    # Pad all question marks and exclamation marks with spaces.
    PAD_QUESTION_EXCLAMATION_MARK = r"([?!])", r" \1 "

    # Handles parentheses, brackets and converts them to PTB symbols.
    PAD_PARENTHESIS = r"([\]\[\(\){}<>])", r" \1 "
    CONVERT_PARENTHESIS_1 = r"\(", "-LRB-"
    CONVERT_PARENTHESIS_2 = r"\)", "-RRB-"
    CONVERT_PARENTHESIS_3 = r"\[", "-LSB-"
    CONVERT_PARENTHESIS_4 = r"\]", "-RSB-"
    CONVERT_PARENTHESIS_5 = r"\{", "-LCB-"
    CONVERT_PARENTHESIS_6 = r"\}", "-RCB-"

    # Pads double dashes with spaces.
    PAD_DOUBLE_DASHES = r"--", " -- "

    # Adds spaces to start and end of string to simplify further regexps.
    PAD_START_OF_STR = r"^", " "
    PAD_END_OF_STR = r"$", " "

    # Converts double quotes to two single quotes and pad with spaces.
    CONVERT_DOUBLE_TO_SINGLE_QUOTES = r'"', " '' "
    # Handles single quote in possessives or close-single-quote.
    HANDLES_SINGLE_QUOTES = r"([^'])' ", r"\1 ' "

    # Pad apostrophe in possessive or close-single-quote.
    APOSTROPHE = r"([^'])'", r"\1 ' "

    # Prepend space on contraction apostrophe.
    CONTRACTION_1 = r"'([sSmMdD]) ", r" '\1 "
    CONTRACTION_2 = r"'ll ", r" 'll "
    CONTRACTION_3 = r"'re ", r" 're "
    CONTRACTION_4 = r"'ve ", r" 've "
    CONTRACTION_5 = r"n't ", r" n't "
    CONTRACTION_6 = r"'LL ", r" 'LL "
    CONTRACTION_7 = r"'RE ", r" 'RE "
    CONTRACTION_8 = r"'VE ", r" 'VE "
    CONTRACTION_9 = r"N'T ", r" N'T "

    # Informal Contractions.
    CONTRACTION_10 = r" ([Cc])annot ", r" \1an not "
    CONTRACTION_11 = r" ([Dd])'ye ", r" \1' ye "
    CONTRACTION_12 = r" ([Gg])imme ", r" \1im me "
    CONTRACTION_13 = r" ([Gg])onna ", r" \1on na "
    CONTRACTION_14 = r" ([Gg])otta ", r" \1ot ta "
    CONTRACTION_15 = r" ([Ll])emme ", r" \1em me "
    CONTRACTION_16 = r" ([Mm])ore$text =~ s='n ", r" \1ore 'n "
    CONTRACTION_17 = r" '([Tt])is ", r" '\1 is "
    CONTRACTION_18 = r" '([Tt])was ", r" '\1 was "
    CONTRACTION_19 = r" ([Ww])anna ", r" \1an na "

    # Clean out extra spaces
    CLEAN_EXTRA_SPACE_1 = r"  *", r" "
    CLEAN_EXTRA_SPACE_2 = r"^ *", r""
    CLEAN_EXTRA_SPACE_3 = r" *$", r""

    # Neurotic Perl regexes to escape special characters.
    # These XML escaping regexes are kept such that tokens generated from
    # NLTK's implementation is consistent with Moses' tokenizer's output.
    # Outside of the MosesTokenizer function, it's strongly encouraged to use
    # nltk.tokenize.util.xml_escape() function instead.
    ESCAPE_AMPERSAND = r"&", r"&amp;"
    ESCAPE_PIPE = r"\|", r"&#124;"
    ESCAPE_LEFT_ANGLE_BRACKET = r"<", r"&lt;"
    ESCAPE_RIGHT_ANGLE_BRACKET = r">", r"&gt;"
    ESCAPE_SINGLE_QUOTE = r"\'", r"&apos;"
    ESCAPE_DOUBLE_QUOTE = r"\"", r"&quot;"
    ESCAPE_LEFT_SQUARE_BRACKET = r"\[", r"&#91;"
    ESCAPE_RIGHT_SQUARE_BRACKET = r"]", r"&#93;"

    EN_SPECIFIC_1 = "([^{alpha}])[']([^{alpha}])".format(alpha=IsAlpha), r"\1 ' \2"
    EN_SPECIFIC_2 = (
        "([^{alpha}{isn}])[']([{alpha}])".format(alpha=IsAlpha, isn=IsN),
        r"\1 ' \2",
    )
    EN_SPECIFIC_3 = "([{alpha}])[']([^{alpha}])".format(alpha=IsAlpha), r"\1 ' \2"
    EN_SPECIFIC_4 = "([{alpha}])[']([{alpha}])".format(alpha=IsAlpha), r"\1 '\2"
    EN_SPECIFIC_5 = "([{isn}])[']([s])".format(isn=IsN), r"\1 '\2"

    ENGLISH_SPECIFIC_APOSTROPHE = [
        EN_SPECIFIC_1,
        EN_SPECIFIC_2,
        EN_SPECIFIC_3,
        EN_SPECIFIC_4,
        EN_SPECIFIC_5,
    ]

    FR_IT_SPECIFIC_1 = "([^{alpha}])[']([^{alpha}])".format(alpha=IsAlpha), r"\1 ' \2"
    FR_IT_SPECIFIC_2 = "([^{alpha}])[']([{alpha}])".format(alpha=IsAlpha), r"\1 ' \2"
    FR_IT_SPECIFIC_3 = "([{alpha}])[']([^{alpha}])".format(alpha=IsAlpha), r"\1 ' \2"
    FR_IT_SPECIFIC_4 = "([{alpha}])[']([{alpha}])".format(alpha=IsAlpha), r"\1' \2"

    FR_IT_SPECIFIC_APOSTROPHE = [
        FR_IT_SPECIFIC_1,
        FR_IT_SPECIFIC_2,
        FR_IT_SPECIFIC_3,
        FR_IT_SPECIFIC_4,
    ]

    NON_SPECIFIC_APOSTROPHE = r"\'", r" \' "

    MOSES_PENN_REGEXES_1 = [
        DEDUPLICATE_SPACE,
        ASCII_JUNK,
        DIRECTIONAL_QUOTE_1,
        DIRECTIONAL_QUOTE_2,
        DIRECTIONAL_QUOTE_3,
        DIRECTIONAL_QUOTE_4,
        DIRECTIONAL_QUOTE_5,
        DIRECTIONAL_QUOTE_6,
        DIRECTIONAL_QUOTE_7,
        DIRECTIONAL_QUOTE_8,
        REPLACE_ELLIPSIS,
        COMMA_1,
        COMMA_2,
        COMMA_3,
        SYMBOLS,
        INTRATOKEN_SLASHES,
        FINAL_PERIOD,
        PAD_QUESTION_EXCLAMATION_MARK,
        PAD_PARENTHESIS,
        CONVERT_PARENTHESIS_1,
        CONVERT_PARENTHESIS_2,
        CONVERT_PARENTHESIS_3,
        CONVERT_PARENTHESIS_4,
        CONVERT_PARENTHESIS_5,
        CONVERT_PARENTHESIS_6,
        PAD_DOUBLE_DASHES,
        PAD_START_OF_STR,
        PAD_END_OF_STR,
        CONVERT_DOUBLE_TO_SINGLE_QUOTES,
        HANDLES_SINGLE_QUOTES,
        APOSTROPHE,
        CONTRACTION_1,
        CONTRACTION_2,
        CONTRACTION_3,
        CONTRACTION_4,
        CONTRACTION_5,
        CONTRACTION_6,
        CONTRACTION_7,
        CONTRACTION_8,
        CONTRACTION_9,
        CONTRACTION_10,
        CONTRACTION_11,
        CONTRACTION_12,
        CONTRACTION_13,
        CONTRACTION_14,
        CONTRACTION_15,
        CONTRACTION_16,
        CONTRACTION_17,
        CONTRACTION_18,
        CONTRACTION_19,
    ]

    MOSES_PENN_REGEXES_2 = [
        RESTORE_ELLIPSIS,
        CLEAN_EXTRA_SPACE_1,
        CLEAN_EXTRA_SPACE_2,
        CLEAN_EXTRA_SPACE_3,
        ESCAPE_AMPERSAND,
        ESCAPE_PIPE,
        ESCAPE_LEFT_ANGLE_BRACKET,
        ESCAPE_RIGHT_ANGLE_BRACKET,
        ESCAPE_SINGLE_QUOTE,
        ESCAPE_DOUBLE_QUOTE,
    ]

    MOSES_ESCAPE_XML_REGEXES = [
        ESCAPE_AMPERSAND,
        ESCAPE_PIPE,
        ESCAPE_LEFT_ANGLE_BRACKET,
        ESCAPE_RIGHT_ANGLE_BRACKET,
        ESCAPE_SINGLE_QUOTE,
        ESCAPE_DOUBLE_QUOTE,
        ESCAPE_LEFT_SQUARE_BRACKET,
        ESCAPE_RIGHT_SQUARE_BRACKET,
    ]

    def __init__(self, lang="en"):
        # Initialize the object.
        super(MosesTokenizer, self).__init__()
        self.lang = lang
        # Initialize the language specific nonbreaking prefixes.
        self.NONBREAKING_PREFIXES = [
            _nbp.strip() for _nbp in nonbreaking_prefixes.words(lang)
        ]
        self.NUMERIC_ONLY_PREFIXES = [
            w.rpartition(" ")[0]
            for w in self.NONBREAKING_PREFIXES
            if self.has_numeric_only(w)
        ]

    def replace_multidots(self, text):
        text = re.sub(r"\.([\.]+)", r" DOTMULTI\1", text)
        while re.search(r"DOTMULTI\.", text):
            text = re.sub(r"DOTMULTI\.([^\.])", r"DOTDOTMULTI \1", text)
            text = re.sub(r"DOTMULTI\.", "DOTDOTMULTI", text)
        return text

    def restore_multidots(self, text):
        while re.search(r"DOTDOTMULTI", text):
            text = re.sub(r"DOTDOTMULTI", r"DOTMULTI.", text)
        return re.sub(r"DOTMULTI", r".", text)

    def islower(self, text):
        return not set(text).difference(set(self.IsLower))

    def isalpha(self, text):
        return not set(text).difference(set(self.IsAlpha))

    def has_numeric_only(self, text):
        return bool(re.search(r"(.*)[\s]+(\#NUMERIC_ONLY\#)", text))

    def handles_nonbreaking_prefixes(self, text):
        # Splits the text into tokens to check for nonbreaking prefixes.
        tokens = text.split()
        num_tokens = len(tokens)
        for i, token in enumerate(tokens):
            # Checks if token ends with a fullstop.
            token_ends_with_period = re.search(r"^(\S+)\.$", token)
            if token_ends_with_period:
                prefix = token_ends_with_period.group(1)
                # Checks for 3 conditions if
                # i.   the prefix contains a fullstop and
                #      any char in the prefix is within the IsAlpha charset
                # ii.  the prefix is in the list of nonbreaking prefixes and
                #      does not contain #NUMERIC_ONLY#
                # iii. the token is not the last token and that the
                #      next token contains all lowercase.
                if (
                    ("." in prefix and self.isalpha(prefix))
                    or (
                        prefix in self.NONBREAKING_PREFIXES
                        and prefix not in self.NUMERIC_ONLY_PREFIXES
                    )
                    or (i != num_tokens - 1 and self.islower(tokens[i + 1]))
                ):
                    pass  # No change to the token.
                # Checks if the prefix is in NUMERIC_ONLY_PREFIXES
                # and ensures that the next word is a digit.
                elif (
                    prefix in self.NUMERIC_ONLY_PREFIXES
                    and (i + 1) < num_tokens
                    and re.search(r"^[0-9]+", tokens[i + 1])
                ):
                    pass  # No change to the token.
                else:  # Otherwise, adds a space after the tokens before a dot.
                    tokens[i] = prefix + " ."
        return " ".join(tokens)  # Stitch the tokens back.

    def escape_xml(self, text):
        for regexp, substitution in self.MOSES_ESCAPE_XML_REGEXES:
            text = re.sub(regexp, substitution, text)
        return text

    def penn_tokenize(self, text, return_str=False):
        """
        This is a Python port of the Penn treebank tokenizer adapted by the Moses
        machine translation community. It's a little different from the
        version in nltk.tokenize.treebank.
        """
        # Converts input string into unicode.
        text = text_type(text)
        # Perform a chain of regex substituitions using MOSES_PENN_REGEXES_1
        for regexp, substitution in self.MOSES_PENN_REGEXES_1:
            text = re.sub(regexp, substitution, text)
        # Handles nonbreaking prefixes.
        text = self.handles_nonbreaking_prefixes(text)
        # Restore ellipsis, clean extra spaces, escape XML symbols.
        for regexp, substitution in self.MOSES_PENN_REGEXES_2:
            text = re.sub(regexp, substitution, text)
        return text if return_str else text.split()

    def tokenize(
        self, text, aggressive_dash_splits=False, return_str=False, escape=True
    ):
        # """
        # Python port of the Moses tokenizer.
        # >>> mtokenizer = MosesTokenizer()
        # >>> text = u'Is 9.5 or 525,600 my favorite number?'
        # >>> print (mtokenizer.tokenize(text, return_str=True))
        # Is 9.5 or 525,600 my favorite number ?
        # >>> text = u'The https://github.com/jonsafari/tok-tok/blob/master/tok-tok.pl is a website with/and/or slashes and sort of weird : things'
        # >>> print (mtokenizer.tokenize(text, return_str=True))
        # The https : / / github.com / jonsafari / tok-tok / blob / master / tok-tok.pl is a website with / and / or slashes and sort of weird : things
        # >>> text = u'This, is a sentence with weird\xbb symbols\u2026 appearing everywhere\xbf'
        # >>> expected = u'This , is a sentence with weird \xbb symbols \u2026 appearing everywhere \xbf'
        # >>> assert mtokenizer.tokenize(text, return_str=True) == expected
        # :param tokens: A single string, i.e. sentence text.
        # :type tokens: str
        # :param aggressive_dash_splits: Option to trigger dash split rules .
        # :type aggressive_dash_splits: bool
        # """
        # Converts input string into unicode.
        text = text_type(text)

        # De-duplicate spaces and clean ASCII junk
        for regexp, substitution in [self.DEDUPLICATE_SPACE, self.ASCII_JUNK]:
            text = re.sub(regexp, substitution, text)
        # Strips heading and trailing spaces.
        text = text.strip()
        # Separate special characters outside of IsAlnum character set.
        regexp, substitution = self.PAD_NOT_ISALNUM
        text = re.sub(regexp, substitution, text)
        # Aggressively splits dashes
        if aggressive_dash_splits:
            regexp, substitution = self.AGGRESSIVE_HYPHEN_SPLIT
            text = re.sub(regexp, substitution, text)
        # Replaces multidots with "DOTDOTMULTI" literal strings.
        text = self.replace_multidots(text)
        # Separate out "," except if within numbers e.g. 5,300
        for regexp, substitution in [self.COMMA_SEPARATE_1, self.COMMA_SEPARATE_2]:
            text = re.sub(regexp, substitution, text)

        # (Language-specific) apostrophe tokenization.
        if self.lang == "en":
            for regexp, substitution in self.ENGLISH_SPECIFIC_APOSTROPHE:
                text = re.sub(regexp, substitution, text)
        elif self.lang in ["fr", "it"]:
            for regexp, substitution in self.FR_IT_SPECIFIC_APOSTROPHE:
                text = re.sub(regexp, substitution, text)
        else:
            regexp, substitution = self.NON_SPECIFIC_APOSTROPHE
            text = re.sub(regexp, substitution, text)

        # Handles nonbreaking prefixes.
        text = self.handles_nonbreaking_prefixes(text)
        # Cleans up extraneous spaces.
        regexp, substitution = self.DEDUPLICATE_SPACE
        text = re.sub(regexp, substitution, text).strip()
        # Restore multidots.
        text = self.restore_multidots(text)
        if escape:
            # Escape XML symbols.
            text = self.escape_xml(text)

        return text if return_str else text.split()


class MosesDetokenizer(TokenizerI):
    # """
    # This is a Python port of the Moses Detokenizer from
    # https://github.com/moses-smt/mosesdecoder/blob/master/scripts/tokenizer/detokenizer.perl
    # >>> tokenizer = MosesTokenizer()
    # >>> text = u'This, is a sentence with weird\xbb symbols\u2026 appearing everywhere\xbf'
    # >>> expected_tokenized = u'This , is a sentence with weird \xbb symbols \u2026 appearing everywhere \xbf'
    # >>> tokenized_text = tokenizer.tokenize(text, return_str=True)
    # >>> tokenized_text == expected_tokenized
    # True
    # >>> detokenizer = MosesDetokenizer()
    # >>> expected_detokenized = u'This, is a sentence with weird \xbb symbols \u2026 appearing everywhere \xbf'
    # >>> detokenized_text = detokenizer.detokenize(tokenized_text.split(), return_str=True)
    # >>> detokenized_text == expected_detokenized
    # True
    # >>> from nltk.tokenize.moses import MosesTokenizer, MosesDetokenizer
    # >>> t, d = MosesTokenizer(), MosesDetokenizer()
    # >>> sent = "This ain't funny. It's actually hillarious, yet double Ls. | [] < > [ ] & You're gonna shake it off? Don't?"
    # >>> expected_tokens = [u'This', u'ain', u'&apos;t', u'funny', u'.', u'It', u'&apos;s', u'actually', u'hillarious', u',', u'yet', u'double', u'Ls', u'.', u'&#124;', u'&#91;', u'&#93;', u'&lt;', u'&gt;', u'&#91;', u'&#93;', u'&amp;', u'You', u'&apos;re', u'gonna', u'shake', u'it', u'off', u'?', u'Don', u'&apos;t', u'?']
    # >>> expected_detokens = "This ain't funny. It's actually hillarious, yet double Ls. | [] < > [] & You're gonna shake it off? Don't?"
    # >>> tokens = t.tokenize(sent)
    # >>> tokens == expected_tokens
    # True
    # >>> detokens = d.detokenize(tokens)
    # >>> " ".join(detokens) == expected_detokens
    # True
    #
    # >>> d.detokenize(expected_tokens, unescape=True)
    # ['This', "ain't", 'funny.', "It's", 'actually', 'hillarious,', 'yet', 'double', 'Ls.', '|', '[]', '<', '>', '[]', '&', "You're", 'gonna', 'shake', 'it', 'off?', "Don't?"]
    # >>> d.detokenize(expected_tokens, unescape=False)
    # ['This', 'ain', '&apos;t', 'funny.', 'It', '&apos;s', 'actually', 'hillarious,', 'yet', 'double', 'Ls.', '&#124;', '&#91;', '&#93;', '&lt;', '&gt;', '&#91;', '&#93;', '&amp;', 'You', '&apos;re', 'gonna', 'shake', 'it', 'off?', 'Don', '&apos;t?']
    # """
    # Currency Symbols.
    IsAlnum = text_type("".join(perluniprops.chars("IsAlnum")))
    IsAlpha = text_type("".join(perluniprops.chars("IsAlpha")))
    IsSc = text_type("".join(perluniprops.chars("IsSc")))

    AGGRESSIVE_HYPHEN_SPLIT = r" \@\-\@ ", r"-"

    # Merge multiple spaces.
    ONE_SPACE = re.compile(r" {2,}"), " "

    # Unescape special characters.
    UNESCAPE_FACTOR_SEPARATOR = r"&#124;", r"|"
    UNESCAPE_LEFT_ANGLE_BRACKET = r"&lt;", r"<"
    UNESCAPE_RIGHT_ANGLE_BRACKET = r"&gt;", r">"
    UNESCAPE_DOUBLE_QUOTE = r"&quot;", r'"'
    UNESCAPE_SINGLE_QUOTE = r"&apos;", r"'"
    UNESCAPE_SYNTAX_NONTERMINAL_LEFT = r"&#91;", r"["
    UNESCAPE_SYNTAX_NONTERMINAL_RIGHT = r"&#93;", r"]"
    UNESCAPE_AMPERSAND = r"&amp;", r"&"
    # The legacy regexes are used to support outputs from older Moses versions.
    UNESCAPE_FACTOR_SEPARATOR_LEGACY = r"&bar;", r"|"
    UNESCAPE_SYNTAX_NONTERMINAL_LEFT_LEGACY = r"&bra;", r"["
    UNESCAPE_SYNTAX_NONTERMINAL_RIGHT_LEGACY = r"&ket;", r"]"

    MOSES_UNESCAPE_XML_REGEXES = [
        UNESCAPE_FACTOR_SEPARATOR_LEGACY,
        UNESCAPE_FACTOR_SEPARATOR,
        UNESCAPE_LEFT_ANGLE_BRACKET,
        UNESCAPE_RIGHT_ANGLE_BRACKET,
        UNESCAPE_SYNTAX_NONTERMINAL_LEFT_LEGACY,
        UNESCAPE_SYNTAX_NONTERMINAL_RIGHT_LEGACY,
        UNESCAPE_DOUBLE_QUOTE,
        UNESCAPE_SINGLE_QUOTE,
        UNESCAPE_SYNTAX_NONTERMINAL_LEFT,
        UNESCAPE_SYNTAX_NONTERMINAL_RIGHT,
        UNESCAPE_AMPERSAND,
    ]

    FINNISH_MORPHSET_1 = [
        "N",
        "n",
        "A",
        "a",
        "\xc4",
        "\xe4",
        "ssa",
        "Ssa",
        "ss\xe4",
        "Ss\xe4",
        "sta",
        "st\xe4",
        "Sta",
        "St\xe4",
        "hun",
        "Hun",
        "hyn",
        "Hyn",
        "han",
        "Han",
        "h\xe4n",
        "H\xe4n",
        "h\xf6n",
        "H\xf6n",
        "un",
        "Un",
        "yn",
        "Yn",
        "an",
        "An",
        "\xe4n",
        "\xc4n",
        "\xf6n",
        "\xd6n",
        "seen",
        "Seen",
        "lla",
        "Lla",
        "ll\xe4",
        "Ll\xe4",
        "lta",
        "Lta",
        "lt\xe4",
        "Lt\xe4",
        "lle",
        "Lle",
        "ksi",
        "Ksi",
        "kse",
        "Kse",
        "tta",
        "Tta",
        "ine",
        "Ine",
    ]

    FINNISH_MORPHSET_2 = ["ni", "si", "mme", "nne", "nsa"]

    FINNISH_MORPHSET_3 = [
        "ko",
        "k\xf6",
        "han",
        "h\xe4n",
        "pa",
        "p\xe4",
        "kaan",
        "k\xe4\xe4n",
        "kin",
    ]

    FINNISH_REGEX = "^({})({})?({})$".format(
        text_type("|".join(FINNISH_MORPHSET_1)),
        text_type("|".join(FINNISH_MORPHSET_2)),
        text_type("|".join(FINNISH_MORPHSET_3)),
    )

    def __init__(self, lang="en"):
        super(MosesDetokenizer, self).__init__()
        self.lang = lang

    def unescape_xml(self, text):
        for regexp, substitution in self.MOSES_UNESCAPE_XML_REGEXES:
            text = re.sub(regexp, substitution, text)
        return text

    def tokenize(self, tokens, return_str=False, unescape=True):
        """
        Python port of the Moses detokenizer.
        :param tokens: A list of strings, i.e. tokenized text.
        :type tokens: list(str)
        :return: str
        """
        # Convert the list of tokens into a string and pad it with spaces.
        text = " {} ".format(" ".join(tokens))
        # Converts input string into unicode.
        text = text_type(text)
        # Detokenize the agressive hyphen split.
        regexp, substitution = self.AGGRESSIVE_HYPHEN_SPLIT
        text = re.sub(regexp, substitution, text)
        if unescape:
            # Unescape the XML symbols.
            text = self.unescape_xml(text)
        # Keep track of no. of quotation marks.
        quote_counts = {"'": 0, '"': 0, "``": 0, "`": 0, "''": 0}

        # The *prepend_space* variable is used to control the "effects" of
        # detokenization as the function loops through the list of tokens and
        # changes the *prepend_space* accordingly as it sequentially checks
        # through the language specific and language independent conditions.
        prepend_space = " "
        detokenized_text = ""
        tokens = text.split()
        # Iterate through every token and apply language specific detokenization rule(s).
        for i, token in enumerate(iter(tokens)):
            # Check if the first char is CJK.
            if is_cjk(token[0]):
                # Perform left shift if this is a second consecutive CJK word.
                if i > 0 and is_cjk(token[-1]):
                    detokenized_text += token
                # But do nothing special if this is a CJK word that doesn't follow a CJK word
                else:
                    detokenized_text += prepend_space + token
                prepend_space = " "

            # If it's a currency symbol.
            elif token in self.IsSc:
                # Perform right shift on currency and other random punctuation items
                detokenized_text += prepend_space + token
                prepend_space = ""

            elif re.search(r"^[\,\.\?\!\:\;\\\%\}\]\)]+$", token):
                # In French, these punctuations are prefixed with a non-breakable space.
                if self.lang == "fr" and re.search(r"^[\?\!\:\;\\\%]$", token):
                    detokenized_text += " "
                # Perform left shift on punctuation items.
                detokenized_text += token
                prepend_space = " "

            elif (
                self.lang == "en"
                and i > 0
                and re.search("^['][{}]".format(self.IsAlpha), token)
            ):
                # and re.search(u'[{}]$'.format(self.IsAlnum), tokens[i-1])):
                # For English, left-shift the contraction.
                detokenized_text += token
                prepend_space = " "

            elif (
                self.lang == "cs"
                and i > 1
                and re.search(
                    r"^[0-9]+$", tokens[-2]
                )  # If the previous previous token is a number.
                and re.search(r"^[.,]$", tokens[-1])  # If previous token is a dot.
                and re.search(r"^[0-9]+$", token)
            ):  # If the current token is a number.
                # In Czech, left-shift floats that are decimal numbers.
                detokenized_text += token
                prepend_space = " "

            elif (
                self.lang in ["fr", "it", "ga"]
                and i <= len(tokens) - 2
                and re.search("[{}][']$".format(self.IsAlpha), token)
                and re.search("^[{}]$".format(self.IsAlpha), tokens[i + 1])
            ):  # If the next token is alpha.
                # For French and Italian, right-shift the contraction.
                detokenized_text += prepend_space + token
                prepend_space = ""

            elif (
                self.lang == "cs"
                and i <= len(tokens) - 3
                and re.search("[{}][']$".format(self.IsAlpha), token)
                and re.search("^[-–]$", tokens[i + 1])
                and re.search("^li$|^mail.*", tokens[i + 2], re.IGNORECASE)
            ):  # In Perl, ($words[$i+2] =~ /^li$|^mail.*/i)
                # In Czech, right-shift "-li" and a few Czech dashed words (e.g. e-mail)
                detokenized_text += prepend_space + token + tokens[i + 1]
                next(tokens, None)  # Advance over the dash
                prepend_space = ""

            # Combine punctuation smartly.
            elif re.search(r"""^[\'\"„“`]+$""", token):
                normalized_quo = token
                if re.search(r"^[„“”]+$", token):
                    normalized_quo = '"'
                quote_counts[normalized_quo] = quote_counts.get(normalized_quo, 0)

                if self.lang == "cs" and token == "„":
                    quote_counts[normalized_quo] = 0
                if self.lang == "cs" and token == "“":
                    quote_counts[normalized_quo] = 1

                if quote_counts[normalized_quo] % 2 == 0:
                    if (
                        self.lang == "en"
                        and token == "'"
                        and i > 0
                        and re.search(r"[s]$", tokens[i - 1])
                    ):
                        # Left shift on single quote for possessives ending
                        # in "s", e.g. "The Jones' house"
                        detokenized_text += token
                        prepend_space = " "
                    else:
                        # Right shift.
                        detokenized_text += prepend_space + token
                        prepend_space = ""
                        quote_counts[normalized_quo] += 1
                else:
                    # Left shift.
                    detokenized_text += token
                    prepend_space = " "
                    quote_counts[normalized_quo] += 1

            elif (
                self.lang == "fi"
                and re.search(r":$", tokens[i - 1])
                and re.search(self.FINNISH_REGEX, token)
            ):
                # Finnish : without intervening space if followed by case suffix
                # EU:N EU:n EU:ssa EU:sta EU:hun EU:iin ...
                detokenized_text += prepend_space + token
                prepend_space = " "

            else:
                detokenized_text += prepend_space + token
                prepend_space = " "

        # Merge multiple spaces.
        regexp, substitution = self.ONE_SPACE
        detokenized_text = re.sub(regexp, substitution, detokenized_text)
        # Removes heading and trailing spaces.
        detokenized_text = detokenized_text.strip()

        return detokenized_text if return_str else detokenized_text.split()

    def detokenize(self, tokens, return_str=False, unescape=True):
        """Duck-typing the abstract *tokenize()*."""
        return self.tokenize(tokens, return_str, unescape)
